Field of the Invention
The present disclosure relates to electric generating elements, and electric generators.
Description of the Related Art
There have been conventionally attempts for effectively utilizing the energy generated by vibrations of a structure, such as roads, bridges, and architecture, vibrations of a moving body, such as cars, and train carriages, and vibration due to human activities. As for a method for effectively utilizing the energy generated by vibrations, there is a method where vibration energy is converted into electric energy. Examples of such a method include a system utilizing a piezoelectric element, and a system utilizing electrostatic induction.
The system utilizing the piezoelectric element uses mainly a ceramic-based piezoelectric element, and utilizes a phenomenon that electric charge is induced at a surface of the piezoelectric element when distortion is applied to the piezoelectric element due to vibrations (see, for example, Japanese Unexamined Patent Application Publication No. 2010-104105).
The system utilizing the electrostatic induction typically uses an electret dielectric retaining electric charge semipermanently (see, for example, Japanese Patent No. 5480414, Japanese Unexamined Patent Application Publication No. 2014-027756, and Japanese Patent No. 5126038). The electret dielectric used in the aforementioned literatures is a material capable of charging the dielectric to generate an electrostatic field semipermanently. Electric charge is induced to an electrode through electrostatic induction by changing a relative position between the electret dielectric and the electrode disposed being distant from the electret dielectric due to vibrations. As a result, electricity is generated.
Moreover, it has been known that extremely high potential can be attained by using an amorphous fluororesin as an electret material, and forming the fluororesin into strip-shaped electret electrodes (see, for example, OMRON Corporation, Development of small “Energy harvesting oscillation device” that generates power with minute vibrations, [online], sited on Nov. 11, 2008, Internet <URL:http://www.omron.co.jp/press/2008/11/c1111.html>).
Furthermore, proposed is an electric generator, which contains a first electrode, a second electrode, a first dielectric layer, and a second dielectric layer, and generates electricity utilizing friction charge (see, for example, US Patent Application Publication No. US 2014/0246950).